The Spectrum sweeps will have zero effect in Contact Mode. This is because 10 slowly moving frequencies are produced as the sweep proceeds. Each frequency requires a portion of the total voltage produced. This is 20 volts, which means that each frequency is allocated 2 volts. This is fine for Remote Mode, but Contact Mode requires 14-20 volts for a frequency to achieve adequate cell penetration.
But this has been changed when Spooky Central was released, and there are additional Spectrum sweeps engineered to take advantage of the large increase in power.